Poisons, toxins and venoms are the defense and attack mechanisms of the natural world. Yet scientists on Nature are finding impressive new possibilities for them – new drugs, new cures, and new ways to save lives at 7 p.m. Sunday.

When Miss Marple learns of the deaths of businessman Rex Fortescue, his wife, Adele, and their housemaid, Gladys, on Masterpiece Mystery at 8 p.m. Sunday, the circumstances mimic the nursery rhyme “Sing a Song of Sixpence.”

From a small-town Texas murder emerged a landmark civil rights case as told on American Experience at 8:30 p.m on Monday. The little-known story of the Mexican American lawyers who took Hernandez v. Texas to the Supreme Court, challenging Jim Crow-style discrimination.

When the American Museum of Natural History’s Hayden Planetarium stopped calling Pluto a planet, director Neil deGrasse Tyson found himself at the center of a firestorm led by angry, Pluto-loving elementary school students. Tag along as NOVA follows Tyson’s study of the solar system’s best-loved non-planet Tuesday at 7 p.m.

Over a single generation, the Web and digital media have remade nearly every aspect of modern culture—from love affairs blossoming in virtual worlds, to the wired classrooms of the future, to military bases where the Air Force is fighting a new form of digital warfare on Frontline at 8:30 p.m. Tuesday.

Neil Young grants rare and unprecedented access for this documentary in which he traces his musical journey in his own words at 7 p.m. Wednesday on American Masters.

In a journey reminiscent of the unexpected zeitgeist success of Hair, A Chorus Line, and Rent, the story behind the success of In the Heights is so organic to New York City that no one expected it to happen. Follow the story on Great Performances at 8:30 p.m. Wednesday.

Citizen Architect: Samuel Mockbee And The Spirit features the late architect and MacArthur “genius” Samuel Mockbee and his Rural Studio, a design/build architecture program in which students create striking architecture for impoverished communities in rural Alabama at 7 p.m. Thursday.

Canadian indie rock marvel Arcade Fire brings its powerful artistic melodrama to the Austin City Limits stage in celebration of its acclaimed second album, The Neon Bible at 7 p.m. Saturday.